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Page 1: BIOSORPTION OF Cd (II)

BIOSORPTION OF Cd (II), Cu (II), Fe (III) AND Pb (II) FROM WATER SYSTEM USING MORINGA

OLEIFERA LEAVES

SABREEN RAMZI ALFARRA

Thesis submitted in fulfilment of the requirements for the award of the degree of

Master of Engineering (Chemical Engineering)

Faculty of Chemical and Natural Resources Engineering UNIVERSITI MALAYSIA PAHANG

NOVEMBER 2015

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ABSTRACT

This study was an attempt to use Moringa oleifera leaves as a natural alternative for synthetic sorbents to reduce the presence of Cd (II), Cu (II), Fe (III) and Pb (II) from water. In this study synthetic water was used to determine the optimum conditions for Cd (II) removal from synthetic water using the biosorbent as first stage of the study. The effect of biosorbent dosage and particle size, contact time, and pH as well as the initial concentration of Cd (II) was studied. Atomic Absorption Spectroscopy (AAS) was used to monitor the experimented ions’ concentration before and after using the biosorbent. Fourier Transform Infrared Spectroscopy (FTIR) was used to monitor biosorbent structure changes before and after loading with Cd (II). The parameters studied were biosorbent dosage 2 to 20 g/l, contact time used was from 2 min to 120 min, biosorbent particle sizes used were 2 mm, 1 mm, 500µm, 250µm, and < 250µm, pH ranges started from 4-10, and the Cd (II) initial concentrations were 1, 3, 5, and 7 ppm. Results revealed that the optimum parameters to reduce 81% of Cd (II) were 12 g/l of biosorbent, 60 min of contact time, <250 µm biosorbent particle sizes with Cd (II) initial concentration of 1 ppm and 50 NTU. The optimized parameters obtained in the study for Cd (II) removal, were applied for Fe (III), Pb (II) and Cu (II) removal, as an attempt to experiment the effect of the optimum parameters of Cd (II) on the other heavy metals. Results showed that the removal efficiency of Moringa oleifera leaves was 81% for Cd (II), 78% for Cu (II), 63.6% for Pb (II) and 62% for Fe (III). It was clear that the achieved optimum conditions give the best removal efficiency percentage on Cd (II) removal. Student t-test results showed that the investigated parameters have an effect on Cd (II) removal with p values <0.05. Biosorption kinetic data were properly fitted with the pseudo-second-order kinetic model. FTIR presented changes in the peaks of the main functional groups and fingerprint area of Moringa oleifera leaves after Cd (II) adsorption experiments; results of FTIR indicated the reactivity of Cd (II) with the biosorbent chemical ingredients and its surface. The SEM results showed that there were differences on the morphological characteristics of the biosorbent, which also indicates the binding process of Cd (II) on the Moringa oleifera leaves. Again, the optimum condition was applied on drainage water, and showed removal efficiency of 83.6% for Cd (II), 73% for Cu (II), 65% for Pb (II) and 52% for Fe (III). Although the results of Moringa oleifera leaves on other heavy metals showed that Moringa oleifera as a biosorbent could reduce the other metals with less percentages which could suggest that Moringa oleifera is a good biosorbent for all the investigated ions generally and Cd (II) particularly. As a conclusion, Moringa oleifera leaves can be a potential and effective, low cost and environmentally friendly biosorbent for the removal of Cd (II) from water systems and reduce the Cu (II), Pb (II) and Fe (III) as well.

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ABSTRAK

Kajian ini merupakan percubaan untuk menyelidik penggunaan daun Moringa oleifora (penjerap bio) sebagai satu kaedah alternatif semulajadi yang bertindak seumpama penjerap sintetik untuk mengurangkan kehadiran Kadmium (Cd (II)), Kuprum (Cu (II)), Ferum (Fe (III)) dan Plumbum (Pb (II)) dalam air. Dalam kajian ini, air sintetik telah digunakan untuk menentukan keadaan optimum bagi penyingkiran Cd (II) daripada air sintetik menggunakan penjerap bio. Kesan dos penjerap bio, saiz zarah, masa sentuh, pH serta kepekatan awal turut dijalankan. Spektroskopi Penyerapan Atom (AAS) telah digunakan untuk memantau kepekatan ion-ion yang dikaji sebelum dan selepas penggunaan penjerap bio. Spektroskopi Inframerah Transformasi Fourier (FTIR) pula digunakan untuk memantau perubahan struktur penjerap bio sebelum dan selepas proses memuatkan dengan Cd (II). Antara parameter yang dikaji ialah dos penjerap bio (2 hingga 20 g/l, masa sentuh yang digunakan antara 2 minit hingga 120 minit, saiz zarah yang digunakan ialah 2 mm, 1 mm, 500µm, 250µm, dan -250µm, pH dalam kadar 4-10, dan kepekatan awal Cd (II) ialah 1, 3, 5, dan 7 ppm. Hasil kajian menunjukkan bahawa dos optimum ialah 12gm/l; masa sentuh ialah 60 minit; saiz zarah ialah -250 µm dan kepekatan awal ialah 1 ppm manakala kekeruhan ialah 50 NTU. Parameter optimum yang dicapai dalam kajian penyingkiran Cd (II) ini telah diuji dalam kajian penyingkiran logam berat yang lain seperti Fe (III), Pb (II) dan Cu (II). Hasil kajian telah menunjukkan kecekapan penyingkiran daun Moringa oleifera ialah sebanyak 81 % untuk Cd (II), 78 % untuk Cu (II), 63.6 % untuk Pb (II) dan 62 % untuk Fe (III). Ini jelas menunjukkan bahawa keadaan optimum yang dicapai sangat berkesan bagi peratusan penyingkiran logam Cd (II). Analisis dengan ujian T juga menunjukkan bahawa parameter yang dikaji mempunyai kesan terhadap penyingkiran Cd (II) dengan nilai p < 0.05. Keputusan FTIR menunjukkan perubahan dalam paruh kelompok fungsian utama dan juga kawasan cap jari Moringa oleifera selepas ujian penjerapan Cd (II). Sekali lagi keadaan optimum telah diuji kesannya terhadap air sisa saliran dan hasil kajian menunjukkan peratusan kecekapan penyingkiran logam berat ialah 83.6% untuk Cd (II), 73% untuk Cu (II), 65% untuk Pb (II) dan 52% untuk Fe (III). Hasil kajian daun Moringa oleifera ke atas logam-logam berat yang lain menunjukkan bahawa ia mampu mengurangkan bahan-bahan logam dengan peratusan yang lebih rendah dan ini menandakan bahawa daun ini sangat sesuai sebagai penjerap bio untuk Cd (II) khususnya dan logam berat lain amnya. Kesimpulannya, daun Moringa oleifera sangat berpotensi dan efektif, mempunyai kos yang rendah dan juga penjerap bio yang mesra alam bagi menyingkirkan Cd (II) dari sistem pengairan.

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TABLE OF CONTENTS

SUPERVISOR’S DECLARATION ........................................................................... ii

STUDENT'S DECLARATION ................................................................................. iii

DEDICATION .......................................................................................................... iv

ACKNOWLEDGEMENT ........................................................................................... v

ABSTRACT .......................................................................................................... vi

ABSTRAK ......................................................................................................... vii

TABLE OF CONTENTS ......................................................................................... viii

LIST OF TABLES ...................................................................................................... xi

LIST OF FIGURES ................................................................................................... xii

LIST OF APPENDICES .......................................................................................... xiii

LIST OF ABBREVIATIONS AND SYMBOLES ................................................. xiv

CHAPTER 1 INTRODUCTION ............................................................................

1.1 Background ........................................................................................................ 1

1.2 Problem statements ............................................................................................ 3

1.3 Research questions ............................................................................................. 4

1.4 Specific objectives ............................................................................................. 4

1.5 Research hypothesis ........................................................................................... 5

1.6 Significance ........................................................................................................ 5

1.7 Dissertation summary ......................................................................................... 5

CHAPTER 2 LITERATURE REVIEW ................................................................

2.1 Background ........................................................................................................ 7

2.1.1 Heavy metals .......................................................................................... 7

2.1.2 Water treatment ...................................................................................... 9

2.1.3 Biosorption of heavy metals ................................................................. 11

2.1.3.1 Agricultural waste biosorbents ............................................... 12

2.1.3.2 Moringa oleifera as biosorbents ............................................. 13

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2.1.4 Biosorption of Cadmium ...................................................................... 15

2.1.4.1 Micororganisms used for Cd (II) removal from water ........... 16

2.1.4.2 Biosorption with agro-industrial waste materials ................... 16

2.1.5 Biosorption of Iron ............................................................................... 21

2.1.6 Biosorption of Copper .......................................................................... 22

2.1.7 Biosorption of Lead .............................................................................. 22

CHAPTER 3 METHODOLOGY ...........................................................................

3.1 Introduction ...................................................................................................... 25

3.2 Analytical techniques ....................................................................................... 25

3.2.1 Atomic Absorption Spectrometry (AAS) ............................................. 25

3.2.2 Fourier Transform Infrared Spectroscopy (FTIR) ................................ 25

3.2.3 Flocculator (Jar Test) ............................................................................ 26

3.2.4 Brunauer-Emmett-Teller (BET) Surface Area Analysis ...................... 27

3.2.5 Scanning Electron Microscope ............................................................. 27

3.2.6 Chemicals ............................................................................................. 28

3.2.7 Equipment ............................................................................................ 28

3.3 Methods ............................................................................................................ 28

3.3.1 Preparation of Biosorbents ................................................................... 28

3.3.2 Preparation of stock solution ................................................................ 29

3.3.3 Preparation of synthetic water .............................................................. 29

3.3.4 Biosorption Batch Experiments ............................................................ 30

3.3.5 Application of Moringa oleifera leaves on Pb(II), Cu(II), and Fe(III) 30

3.3.6 Preparation of 1D and 2D Fourier transform infrared spectroscopy

(FTIR) sample ...................................................................................... 31

3.3.7 Preparation for SEM analysis ............................................................... 31

3.3.8 Preparation for Surface area analysis ................................................... 31

3.3.9 Preparation for Heavy Metal Removal Analysis .................................. 31

3.3.10 Preparation for Turbidity Measurement ............................................... 32

3.3.11 Biosorption kinetics procedures ........................................................... 32

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CHAPTER 4 RESULTS AND DISCUSSIONS .....................................................

4.1 Introduction ...................................................................................................... 34

4.2 Effect of parameters on Cd (II) removal .......................................................... 34

4.2.1 Biosorbent dose effect .......................................................................... 34

4.2.2 Contact time effect ............................................................................... 37

4.2.3 Biosorbent particle size effect .............................................................. 40

4.2.4 Water turbidity effect on Cd (II) removal ............................................ 41

4.2.5 Biosorption kinetics .............................................................................. 42

4.2.5.1 Pseudo-first order kinetics ...................................................... 42

4.2.5.2 Pseudo-second order kinetics ................................................. 43

4.2.6 FTIR analysis ....................................................................................... 45

4.2.7 SEM analysis ........................................................................................ 47

4.2.8 Biosorption of Pb(II), Cu(II) and Fe(III) from water by Moringa

oleifera leaves ....................................................................................... 48

4.3 Effect of Moringa oleifera on heavy metal removal from drainage water ...... 50

4.4 Conclusion ........................................................................................................ 51

CHAPTER 5 CONCLUSION AND RECOMMENDATIONS ............................

5.1 Conclusion ........................................................................................................ 52

5.2 Recommendations and future work ................................................................. 53

REFERENCES ......................................................................................................... 55

APPENDICES ......................................................................................................... 68

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LIST OF TABLES

TABLE NO.

TITLE PAGE

2.1 Heavy metals sources and its toxicity 8

2.2 Advantages and disadvantages of some techniques to remove heavy metal from water

10

2.3 Advantages and disadvantages of used biosorbents 11

2.4 Factors affecting biosorption 12

4.1 The removal efficiency percentage at different times with different Cd (II) concentration

39

4.2 The effect of Moringa oleifera leaves particle sizes on the Cd (II) removal efficiency

40

4.3 The different turbidity and the optimum RE% for each Cd (II) concentration

41

4.4 Kinetic constant for Cadmium (II) biosorption onto Moringa oleifera leaves.

42

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LIST OF FIGURES

FIGURES NO.

TITLE PAGE

2.1 Traditional Medicinal Uses of Moringa oleifera leaves 14

3.1 Sample running in the Jar test 26

3.2 Flow chart of the experimental work involved in this study 28

3.3 AAS standard curve of the Cd (II) concentrations (0.5, 1, 1.5 ppm).

31

4.1 The removal efficiency of different dose at different Cd (II) concentrations at 200 rpm, 60 min contact time, <250µ particle size and 200 NTU

35

4.2 The amount of Cd (II) removed by different doses of Moringa oleifera at the different initial concentration, 200 rpm, 60 min contact time, < 250µ particle size and 200 NTU

35

4.3 The pseudo-first order kinetic plot for the adsorption of cadmium ions onto Moringa oleifera leaves

40

4.4 The pseudo-second order kinetic plot for the adsorption of cadmium ions onto Moringa oleifera leaves

45

4.5 2D FTIR spectrum of Moringa oleifera leaves before and after biosorption of Cd

46

4.6 1D FTIR of Moringa oleifera leaves contents before and after biosorption of Cd

44

4.7 Scanning electron micrographs of Moringa oleifera leaves before and after Cd (II) adsorption, where (a) represents the morphology before and (b) represents the morphology after Cd (II) adsorption

45

4.8 The removal efficiency of Moringa oleifera leaves on different heavy metals from synthetic water

46

4.9 The removal efficiency of Moringa oleifera leaves on heavy metal removal from waste water

48

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LIST OF APPENDICES

APPENDIX NO.

TITLE PAGE

1 List of publications and exhibition 68

2 Atomic Absorption Spectroscopy 69

3 Flocculator (jar test) used for coagulation -flocculation process

70

4 Moringa oleifera tree leaves 71 5 Drying Moringa oleifera leaves under the

sun 72

6 Preparation of the sample for the experiment before and after filtration

73

7 Surface area analyser instrument results

74

8 AAS data 75

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LIST OF ABBREVIATIONS AND SYMBOLES

1D One Dimensional

2D Two Dimensional

WHO World Health Organization

Cd Cadmium

Pb Lead

Cu Copper

Fe Iron

MO Moringa oleifera

RE Removal Efficiency

K1 Pseudo-first-order rate constant of biosorption

(min−1)

K2 Pseudo-second-order rate constant of

biosorption (gmg−1min−1)

qt Metal ion adsorbed on biosorbent at a given time

(mg g−1)

qe Metal ion adsorbed on biosorbent at equilibrium

(mg g−1)

R2 Regression correlation coefficient

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CHAPTER 1

INTRODUCTION

1.1 BACKGROUND

Every day, there are thousands of chemicals discharged directly and indirectly

into water bodies without further treatment for elimination of the included harmful

compounds (Salim et al., 2008). Heavy metals are without doubt well thought-out as

the most hazardous and harmful metals even if they are present as traces, since they

accumulate in the tissue of living organisms (Rao et al., 2010; Khairy et al., 2014).

Conventional processes for removal of metals from water include chemical

precipitation oxidation-reduction, filtration, electrochemical methods and other

complicated separation procedures using membranes. Such methods showed to be not

effective and not economically possible for the treatment of low heavy metals

concentrations (Kelly-Vargas et al., 2012; Lim and Aris, 2014). Therefore, new

alternative methods are needed to find the best ecological and economical techniques

for biosorption of heavy metals from water.

Biosorption describes any system which includes a sorbate working together

with a biosorbent resulting in an accumulation at the sorbate–biosorbent interface, and

therefore a decrease of sorbent concentration in the solution (Sasaki et al., 2013).

Biosorption is a property of both living and dead organisms, and has been exploited as

a promising biotechnology because of its simplicity (Bilal et al., 2013). Accordingly,

biosorption can be defined as the removal of substances from solution by biological

materials (Gadd, 2001).

Moringa oleifera is a native tree of the sub-Himalayan parts of Northwest

India, Pakistan and Afghanistan. It is now widely cultivated across Africa, South

America, most parts of South - East Asia for example: Malaysia, Indonesia and

Thailand (Reddy et al., 2011).

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Moringa oleifera is a multipurpose tree with most of its parts being useful for a

number of applications. It is generally used in a number of developing countries as a

vegetable, medical plant and a source of vegetable oil. It has an impressive range of

medicinal uses with high nutritional value (Anwar et al., 2007). On the other hand,

Moringa oleifera seeds have been found to be a natural coagulant, flocculants,

softener, disinfectant, and sludge conditioner (Jahn et al., 1986; Suarez et al., 2003;

Nand et al., 2012), heavy metal remover in water and wastewater treatment (Alves

and Coelho, 2013; Obuseng et al., 2012).

One of the heavy metals in water is Cadmium (II); it is naturally present in the

environment by the gradual process of erosion and abrasion of rocks and soils, and

from singular events such as forest fires and volcanic eruptions. It is therefore

naturally present everywhere in air, water, soils and foodstuffs (Mahvi et al., 2008).

Cadmium is one of the heavy metals which is highly toxic to humans, plants

and animals and it is responsible for causing kidney damage, renal disorder, high

blood pressure, bone fractures, and destruction of red blood cells (Drasch, 1983;

Purkayastha et al., 2014). According to the World Health Organization (WHO), the

maximum accepted level of Cd (II) in water is 0.005 mg/l (Abaliwano et al., 2008)

Meanwhile, Ministry of Health Malaysia (MOH) recommends that Cd (II) limits in

drinking water should be 0.003 mg/l (MOH, 2015).

Another heavy metal is iron, which is the most plentiful element on earth. It is

an essential element in human nutrition and plant metabolism, and it is used in a

variety of industrial processes. In industries, it is used as a construction material and

to create pigments. For humans, it is required for haemoglobin to transport oxygen

from lungs to cells. However, high levels of iron can be fatal. Iron is commonly found

in many industrial wastewaters. Generally, it is present in the water in the ferric state

and enters the water bodies in the form of ferrous ion Fe (II), which can be oxidized to

ferric ion Fe (III) by oxygen dissolved in water (Ahalya et al., 2003). The maximum

accepted level of Fe (III) in water is 0.3 mg/l (Colter and Mahler, 2006), Meanwhile,

Ministry of Health Malaysia recommends that Fe (III) limits in drinking water should

be 1 mg/l (MOH, 2015).

Copper is both an essential nutrient and a drinking water contaminant. It is an

important trace element required by humans for its role in enzyme synthesis, tissue

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and bone development (Nand et al., 2012). However, excessive amounts of copper

consumed is toxic and carcinogenic and it leads to its deposition in the liver and

causes many diseases such as Wilson disease, liver and kidney failure and finally

gastrointestinal bleeding (Al Bsoul et al., 2014).

The excessive amounts of Cu (II) in fresh water resources and aquatic

ecosystem damage the osmo-regulatory mechanism of the freshwater animals and

cause mutagenesis in humans (Bilal et al., 2013). Large quantities of copper are

released to the environment by discarding industrial waste without further treatment

(Demirbaş et al., 2008). According to World Health Organization (WHO) the

permissible limit of Cu (II) in water is 1.5 mg/l (Bilal et al., 2013). According to the

Ministry of Health Malaysia the acceptable limits of Cu (II) in drinking water should

be 1 mg/l (MOH, 2015).

Lead occurs in water due to numerous industrial and mining sources and is the

most widely spread of all toxic metals. The overload amount of lead in water causes

severe problems such as anaemia, encephalopathy, hepatitis and kidney disease

(Shafaghat et al., 2014; Putra et al., 2014). According to World Health Organization

(WHO) the highest desirable limit of Pb (II) is 0.05 mg/l (Mataka et al., 2006).

Meanwhile, Ministry of Health Malaysia recommends that Pb (II) limits in drinking

water should be 0.01 mg/l (MOH, 2015).

Since Malaysia is widely recognized as one of the centres of biological

diversity, rich with wild plants, it will be beneficial for the researchers to further

screen the valuable biosorbent. All of these resources could provide renewable useful

products not only for the current generation but also for the future generations to

come. Hence, this study is initiated to target the miracle tree Moringa oleifera to be

used as a potent biosorbent for the Cd (II), Pb (II), Cu (II) and Fe (III) ions. To help in

finding an alternative methods to treat water, which could be economically and

environmental friendly techniques.

1.2 PROBLEM STATEMENTS

Cadmium and other heavy metals present in water are harmful and poisonous

and need to be removed from water; using natural biosorbent is one of the solutions.

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In aquatic ecosystems water contamination by heavy metals is one of the main

types of pollutions that may stress the biological systems. Great amount of several

heavy metals including Cd (II) are discharged into water systems as contaminants by

anthropogenic activities (Ebrahimpour and Mushrifah, 2008; Sany et al., 2013). In

Malaysia there are different industrial resources for Cd (II) and heavy metals.

Petroleum refinery could be a source of many heavy metals including Cd (II) (Wuyep

et al., 2007). Few studies reported the removal of some heavy metals from water by

Moringa oleifera, however the use of Moringa oleifera leaves to adsorb cadmium

from water still not too much targeted and minimally used in this field, thus more

research is needed. Therefore, this project is an investigation of removing mainly

cadmium and other heavy metals from water, which will be carried out.

1.3 RESEARCH QUESTIONS

1. Can Moringa oleifera leaves used as a biosorbent?

2. Do Moringa oleifera leaves have the ability to remove Cd (II) from

water systems?

3. Does Cd (II) affect the phytochemistry of Moringa oleifera leaves?

4. What is the effect of Cd (II) on the morphological characteristics of

Moringa oleifera?

5. What are the optimum conditions that give the maximum removal of

Cd (II) by Moringa oleifera leaves?

6. Could the Moringa oleifera leaves remove the other heavy metals

from water systems?

1.4 SPECIFIC OBJECTIVES

1. To remove cadmium from water using Moringa oleifera leaves and

to find the best conditions that can be used for Cd (II) removal from

water.

2. To know the effect of Cd (II) adsorption on Moringa oleifera leaves

phytochemistry structure.

3. To examine the effect of Cd (II) on the morphological properties of

Moringa oleifera leaves.

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4. To study the biosorption kinetics of Cd (II) up taken by Moringa

oleifera leaves.

5. To apply the optimum conditions for the removal of Cd (II) on other

heavy metals such as Fe (III), Cu (II) and Pb (II) from drainage

water.

1.5 RESEARCH HYPOTHESIS

Moringa oleifera leaves could remove the Cd (II) from the contaminated water

system, which will be useful in drinking and wastewater treatment. This leaves was

chosen because Moringa oleifera tree can be of great benefit to Malaysia as new crop

for producing different product from all parts of the tree and the leaves is one of the

parts that can be a good source of raw material such as adsorbent.

1.6 SIGNIFICANCE

The results of this project will serve in treating water by removing cadmium

and other heavy metals using natural and environmentally friendly materials which

can be used in many countries especially Malaysia.

1.7 DISSERTATION SUMMARY

This dissertation includes five chapters. Chapter one is the introduction

chapter, which included the background of the study, problem statement, research

questions, specific objectives, research hypothesis and significance.

Chapter two the literatures review chapter, which included the review of the

previous reports and studies that related to the heavy metals and biosorbent of heavy

metals.

Chapter Three the methodology chapter covered different stages, which

included collecting the leaves from the available sources around Kuantan, Pahang,

Malaysia. Preparing leaves, biosorbent tests and investigating the optimum conditions

for Cd (II) removal from synthetic water.

The first stage, reported in Chapter Three, covered the preparation of Moringa

oleifera leaves, which included the leave drying, grinding and sieving to different

sizes, in addition to the synthetic water and heavy metal's stock solutions preparation.

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Then, the second stage was continued with the optimization of the different

parameters started with biosorbent dosage, contact time, particle size, pH effect, water

turbidity and initial heavy metal concentrations.

Optimization of the parameters started with dosage optimization. After getting

the optimum dosage, it was maintained in the other experiment and other parameters

were targeted and optimized. Atomic Absorption spectroscopy (AAS) was used to

determine the heavy metals before and after biosorption by Moringa oleifera leaves.

FTIR was used to investigate the functional groups of Moringa oleifera leaves and

change in the structure before and after loading with Cd (II). In addition to that

Electron Scanning Microscopy was done to follow the changes occurred on Moringa

oleifera leaves morphology after the biosorption process. Surface Area Analyser (BET

test) was used to investigate the effect of the particle size on the biosorption process.

Lastly, the optimized parameters achieved in the study for Cd (II) removal, were

applied on Fe (III), Pb (II) and Cu (II) in one experiment to test the optimized

parameters on these ions and to compare the ability of Moringa oleifera leaves

biosorption of these ions.

At the end, it can be concluded that the study answered the main research

questions, which can summarize that Moringa oleifera leaves could be a potential

biosorbent for Cd (II) and the other targeted heavy metals from water systems. It also

answered the question that Cd (II) could make changes on the structure and the

morphological characteristics of Moringa oleifera leaves.

Chapter four covered the results and discussion. The last chapter in this

dissertation chapter five includes the conclusion and recommendations.

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CHAPTER 2

LITERATURE REVIEW

2.1 BACKGROUND

2.1.1 Heavy metals

This entire review revised the most recent studies on biosorbents used for

heavy metals removal such as plant leaves, seeds, barks, agricultural wastes and

biological material and their efficiency on heavy metals adsorption, such as: lead,

cadmium, iron and copper. This literature revision also mentioned the conventional

methods used for heavy metals removal and the advantages and disadvantages of

them. Furthermore, it represents the advantages and disadvantages of common

biosorbents and the effect of several factors that influence the biosorption process.

Every day, there are thousands of chemicals discharged directly and indirectly

into water bodies as industrial waste causing serious air, soil, and water contamination

without further treatment for elimination of the included harmful compounds (Salim et

al., 2008; Khairy et al., 2014). Heavy metals are without doubt well thought-out as the

most hazardous and harmful metals even if they are present as traces, since they

accumulate in the tissue of living organisms (Rao et al., 2010; Khairy et al., 2014).

Most of the metals are carcinogenic, teratogenic and cause severe health problems like

organ damage, reduced growth and development, nervous system impairments and

oxidative stress. Heavy metals introduced into water by several industries such as

mining, electroplating, petroleum refining (Rao et al., 2010) and other industries with

its toxicity which is presented in Table 2.1.

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Table 2.1: Heavy metal sources and toxicity

Metal Source Toxic effect WHO Permissible

limit mg/l

MOH permissible

limit mg/l

Reference

Cadmium Electroplating, smelting, alloy manufacturing, pigments, plastic and mining

Itai–Itai disease, carcinogenic, renal disturbances, lung insufficiency, bone lesions, cancers, hypertension, weight loss

0.005 0.003 (Sharma and Bhattacharyya, 2005; Momodu and Anyakora, 2010; Singh et al., 2005; MOH, 2015)

Lead Manufacturing of batteries, pigments Electroplating, ammunition

Anaemia, brain damage, anorexia, malaise, loss of appetite

0.05 0.01 (Low et al., 2000; Ali et al., 2013; Mataka et al., 2006; MOH, 2015)

Chromium Electroplating, paints and pigments, metal processing, steel fabrication and canning industry

Epigastric pain, nausea, vomiting, severe diarrhoea, lung tumours, Carcinogenic, mutagenic, teratogenic

0.03 0.05 (Ali et al., 2013; Rao et al., 2010; Singh et al., 2005; MOH, 2015)

Copper Electronics plating, paint manufacturing, wire drawing, copper polishing, and printing operations

Reproductive and developmental toxicity, neurotoxicity, and acute toxicity, dizziness, diarrhoea

1.5 1 (Bilal et al., 2013; MOH, 2015)

Arsenic Smelting, mining, energy production from fossil fuels, rock sediment’s

Bone marrow depression, haemolysis, liver tumours, gastrointestinal symptoms, cardiovascular and nervous system functions disturbances,

0.02 0.01 (Momodu and Anyakora, 2010; MOH, 2015)

Mercury Volcanic eruptions, forest fires, battery manufacturing

Corrosive to skin, eyes, muscles, neurological and renal disturbances,

0.002 0.001 (Farooq et al., 2010; MOH, 2015)

Nickel Copper sulphate manufacture, electroplating, non-ferrous metal, mineral processing,

Reduced lung function, lung cancer, chronic bronchitis, dermatitis, and chronic asthma.

0.03 0.02 (Febrianto et al., 2009; Öztürk, 2007; MOH, 2015)

Zinc Mining and manufacturing processes

Causes short term ‘‘metal-fume fever,” gastrointestinal distress, nausea and diarrhoea

4 3 (Farooq et al., 2010; MOH, 2015)

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2.1.2 Water treatment

Inorganic coagulants for water treatment are used in a wide-range. Aluminium

sulphate is an examples of the inorganic coagulant, which is the most commonly used

coagulant in the developing countries (Farooq et al., 2010). However, aluminium

sulphate is reported to cause some neurological diseases for instance pre-senile

dementia or Alzheimer’s disease (Othman et al., 2010).

The currently used techniques contain several constraints in the removal of

heavy metals from water (Abaliwano et al., 2008), such methods showed to not be

effective and not economically possible for the treatment of low concentrations

(Kelly-Vargas et al., 2012). Therefore new alternative methods need to be explored to

find the best ecological and economical techniques to remove the heavy metals from

water. A number of effective biosorbents from plant resources have been investigated

which will be mentioned in this chapter. Table 2.2, illustrates the advantages and

disadvantages of some techniques to remove heavy metals.

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Table 2.2: Advantages and disadvantages of several techniques used currently to remove heavy metal from water

Method Advantages Disadvantages References

Chemical Precipitation

Inexpensive. Simple. Most of the metals can be removed.

Disposal problems. High solid waste produced.

(Abaliwano et al., 2008)

Ion-exchange Metal selective. High regeneration of Materials.

Fewer numbers of metal ions removed. High cost

(Rao et al., 2010)

Chemical coagulation

De watering. Sludge settling.

Large consumption of chemicals. High cost.

(Abaliwano et al., 2008)

Membrane process and ultra filtration

High efficiency (>95) Less solid waste produced Less chemical consumption.

High running cost. Low flow rates.

(Fu and Wang, 2011)

Natural zeolite Relatively less costly materials. Most of the metals can be removed. Low efficiency.

(Fu and Wang, 2011)

Electrochemical methods

Pure metals can be achieved. No consumption of chemicals.

High running cost. High capital cost.

(Rao et al., 2010)

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2.1.3 Biosorption of heavy metals

Biosorption is a property of both living and dead organisms (and their

components), and has been exploited as a promising biotechnology because of its

simplicity (Bilal et al., 2013). Accordingly, Biosorption can be defined as the removal

of substances from solution by biological materials (Gadd, 2001); Table 2.3 represents

the advantages and disadvantages of common biosorbents.

Table 2.3: Advantages and disadvantages of common biosorbents

Advantages Disadvantages

Low operation costs if low-cost sorbents are used. (Fu and Wang, 2011) Low quantity of sewage sludge disposed. (Gadd, 2008) COD of wastewater does not increase. (Sahmoune et al., 2011) The process is simple in operation and very rapid. (Sahmoune et al., 2011) Biosorbents are selective and regenerable. (Fu and Wang, 2011)

Shorter lifetime of biosorbents when compared with conventional sorbents. (Fu and Wang, 2011) Fast saturation i.e. when metal interactive sites are occupied.(Gadd, 2008) Recyclable and decomposable properties of biomass are delaying their long-term applications in adsorption processes. (Sahmoune et al., 2011) The characteristics of the biosorbents cannot be biologically controlled.(Ahalya et al., 2003)

Biosorption describes any system that includes a sorbate (an atom, molecule, a

molecular ion) working together with a biosorbent (a solid surface of a biological

matrix) resulting in an accumulation at the sorbate–biosorbent interface, and therefore

a decrease of sorbent concentration in the solution (Sasaki et al., 2013).

Since biosorption is determined by equilibrium, several factors have an impact

on heavy metals removal is summarized in Table 2.4 (Chojnacka, 2010).

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Table 2.4: Factors affecting biosorption Factors Effects

Biosorbent dosage It decreases the quantity of biosorbed pollutant per unit weight of biosorbent, but increases its removal efficiency

Initial pollutant Concentration

It increases the quantity of biosorbed pollutant per unit weight of biosorbent, but decreases its removal efficiency

Solution pH It enhances biosorptive removal of cationic metals or basic dyes, but reduces that of anionic metals or acidic dyes

Biosorbent size It is favourable for batch process due to higher surface area of the biosorbent, but not for column process due to its low mechanical strength and clogging of the column

Other pollutant Concentration

If coexisting pollutant competes with a target pollutant for binding sites or forms any complex with it, higher concentration of other pollutants will reduce biosorptive removal of the target pollutant

2.1.3.1 Agricultural waste Biosorbents

Agricultural waste materials are usually composed of lignin and cellulose as

the main constituents (Beveridge and Murray, 1980). Other components are

hemicelluloses, lipids, proteins, simple sugars, starches, water, hydrocarbons, ash and

many more compounds that contain a variety of functional groups present in the

binding process; for example carboxyl, amino, alcohol and esters (Gupta and Ali,

2000). These groups are assumed to have the ability to bind heavy metal by

replacement of hydrogen ions for metal ions in solution or by donation of an electron

pair from these groups to form complexes with the metal ions in solution. Researchers

reported the relation between the presence of various functional groups and their

binding with heavy metals during the biosorption process (Tarley and Arruda, 2004).

A number of studies have highlighted the potential of inexpensive adsorbents prepared

from an agricultural by-product (Bailey et al., 1999; Babel and Kurniawan, 2003;

Kurniawan et al., 2006; Sud et al., 2008; Reddy et al., 2009). Moreover heavy metal

removal by agro based waste material was reported by (Qaiser et al., 2007) and

agricultural waste okra biomass (Singha and Guleria, 2015).

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2.1.3.2 Moringa oleifera as biosorbents

Moringa oleifera is a fast growing tree which can tolerate drought, bacteria and

fungi (Karmakar et al., 2010). It can also tolerate rainfall ranging from 25 to 300 cm

with temperatures ranging from 19 to 28 ºC (Karmakar et al., 2010). The tree ranges

in height from 5-12 meters and sometimes even 15 meters (Tsaknis et al., 1999). In

some parts of the world Moringa oleifera is referred to as the ‘drumstick tree’ or the

‘horse radish tree’, and kelor tree (Anwar and Bhanger, 2003). While in the Nile

valley, the name of the tree is ‘Shagara al Rauwaq’, which means ‘tree for purifying’

(Anwar et al., 2007). In Pakistan, Moringa oleifera is locally known as ‘Sohanjna’ and

is grown and cultivated all over the country (Anwar et al., 2007). In the Philippines, it

is known as ‘mother’s best friend’ because of its utilization to increase the woman’s

milk production and is sometimes prescribed for anaemia (Estrella et al., 2000;

Siddhuraju and Becker, 2003).

Moringa oleifera is a multi purposes tree with most of its parts being useful for

a number of applications. It is generally used in a number of developing countries as a

vegetable, medical plant and a source of vegetable oil. It has an impressive range of

medicinal uses with high nutritional value (Anwar et al., 2007). Each part of this plant

contains a profile of important minerals, and is a good source of protein, vitamins, β -

carotene, amino acids and various phenolic. The Moringa oleifera plant provides a

rich and rare combination of zeatin, quercetin, β - sitosterol, caffeoylquinic acid and

kaempferol (Siddhuraju and Becker, 2003). The fresh leaves are rich in vitamin A and

C. The leaves extract has therapeutic potential for the prevention of some diseases

(Anwar et al., 2007), Figure 2.1, shows some traditional medicinal uses of Moringa

oleifera leaves.

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Figure 2.1: Traditional Medicinal Uses of Moringa oleifera leaves (Anwar et al., 2007)

Moringa oleifera seeds have been found to be a natural coagulant, flocculants,

softener, disinfectant, and sludge conditioner (Muyibi and Evison, 1995; Jahn et al.,

1986; Abaliwano et al., 2008; Suarez et al., 2003), heavy metal remover in water and

wastewater treatment (Alves and Coelho, 2013; Obuseng et al., 2012; Reddy et al.,

2011; Reddy et al., 2010). The Moringa oleifera seeds also have antibacterial activity

(Broin et al., 2002). Extracted seed oil is a good edible oil, lubricant oil and as

feedstock for biodiesel (Karmakar et al., 2010; Mani et al., 2007; Rashid et al., 2008).

The seed husk and pods left over can be steamed activated to produce a high quality

activated carbon (Nadeem et al., 2006). The flower and fruits are used as vegetables

and the trunk is used in the paper industry (Tsaknis et al., 1999). The roots are used

for medicinal purposes (Karadi et al., 2006).

The residual solids left from oil extraction and filtration process can be

considered as animal feed with high nutritional value, and as soil fertilizer.


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